commit ead5204b91ff4376bd97dc56deed8f06399ab16e
Author: Stephen Wadeley <swadeley(a)redhat.com>
Date: Fri Sep 26 12:50:22 2014 +0200
crony: Docs QA Feedback
en-US/Configuring_NTP_Using_the_chrony_Suite.xml | 63 +++++++++-------------
1 files changed, 25 insertions(+), 38 deletions(-)
---
diff --git a/en-US/Configuring_NTP_Using_the_chrony_Suite.xml
b/en-US/Configuring_NTP_Using_the_chrony_Suite.xml
index b1fe1e1..efaff6d 100644
--- a/en-US/Configuring_NTP_Using_the_chrony_Suite.xml
+++ b/en-US/Configuring_NTP_Using_the_chrony_Suite.xml
@@ -29,7 +29,7 @@ There is a choice between the daemons <systemitem
class="daemon">ntpd</systemite
<itemizedlist>
<listitem>
<para>
- <systemitem class="daemon">chronyd</systemitem> can work well
when external time references are only intermittently accessible whereas <systemitem
class="daemon">ntpd</systemitem> needs regular polling of time
reference to work well.
+ <systemitem class="daemon">chronyd</systemitem> can work well
when external time references are only intermittently accessible, whereas <systemitem
class="daemon">ntpd</systemitem> needs regular polling of time
reference to work well.
</para>
</listitem>
<listitem>
@@ -49,7 +49,7 @@ There is a choice between the daemons <systemitem
class="daemon">ntpd</systemite
</listitem>
<listitem>
<para>
- <systemitem class="daemon">chronyd</systemitem> in the
default configuration never steps the time after the clock has been synchronized at system
start, in order not to upset other running programs. <systemitem
class="daemon">ntpd</systemitem> can be configured to never step the
time too, but it has to use a different means of adjusting the clock, which has some
disadvantages.
+ In the default configuration, <systemitem
class="daemon">chronyd</systemitem> never steps the time after the
clock has been synchronized at system start, in order not to upset other running programs.
<systemitem class="daemon">ntpd</systemitem> can be configured to
never step the time too, but it has to use a different means of adjusting the clock, which
has some disadvantages.
</para>
</listitem>
<listitem>
@@ -66,7 +66,7 @@ Things <systemitem
class="daemon">chronyd</systemitem> can do that <systemitem c
<listitem>
<para>
- <systemitem class="daemon">chronyd</systemitem> provides
support for isolated networks where the only method of time correction is manual entry.
For example, by the administrator looking at a clock. <systemitem
class="daemon">chronyd</systemitem> can look at the errors corrected at
different updates to estimate the rate at which the computer gains or loses time, and use
this estimate to trim the computer clock subsequently.
+ <systemitem class="daemon">chronyd</systemitem> provides
support for isolated networks where the only method of time correction is manual entry.
For example, by the administrator looking at a clock. <systemitem
class="daemon">chronyd</systemitem> can examine the errors corrected at
different updates to estimate the rate at which the computer gains or loses time, and use
this estimate to trim the computer clock subsequently.
</para>
</listitem>
<listitem>
@@ -121,13 +121,13 @@ Things <systemitem
class="daemon">ntpd</systemitem> can do that <systemitem clas
<section id="sect-Understanding_chronyc">
<title>Understanding chronyc</title>
<para>
- The <application>chrony</application> daemon, <systemitem
class="daemon">chronyd</systemitem>, can be controlled by the command
line utility <application>chronyc</application>. This utility provides a
command prompt which allows entering of a number of commands to make changes to
<systemitem class="daemon">chronyd</systemitem>. The default
configuration is for <systemitem class="daemon">chronyd</systemitem>
to only accept commands from a local instance of
<application>chronyc</application>, but
<application>chronyc</application> can be used to alter the configuration so
that <systemitem class="daemon">chronyd</systemitem> will allow
external control. That is to say, <application>chronyc</application> can be
run remotely after first configuring <systemitem
class="daemon">chronyd</systemitem> to accept remote connections. The
<systemitem class="protocol">IP</systemitem> addresses allowed to
connect to <systemitem class="daemon">chronyd</systemitem> should be
tightly control
led.</para>
+ The <application>chrony</application> daemon, <systemitem
class="daemon">chronyd</systemitem>, can be controlled by the command
line utility <application>chronyc</application>. This utility provides a
command prompt which allows entering of a number of commands to make changes to
<systemitem class="daemon">chronyd</systemitem>. The default
configuration is for <systemitem class="daemon">chronyd</systemitem>
to only accept commands from a local instance of
<application>chronyc</application>, but
<application>chronyc</application> can be used to alter the configuration so
that <systemitem class="daemon">chronyd</systemitem> will allow
external control. <application>chronyc</application> can be run remotely after
first configuring <systemitem class="daemon">chronyd</systemitem> to
accept remote connections. The <systemitem
class="protocol">IP</systemitem> addresses allowed to connect to
<systemitem class="daemon">chronyd</systemitem> should be tightly
controlled.</para>
</section>
<section id="sect-Understanding_the_chrony_configuration_commands">
<title>Understanding the chrony Configuration Commands</title>
<para>
- The default configuration file for <systemitem
class="daemon">chronyd</systemitem> is
<filename>/etc/chrony.conf</filename>. The <option>-f</option>
option can be used to specify an alternate configuration file path. See the <systemitem
class="daemon">chronyd</systemitem> man page for further options. For a
complete list of the directives that can be used see <ulink
url="http://chrony.tuxfamily.org/manual.html#Configuration-file"...
pubwork="webpage">http://chrony.tuxfamily.org/manual.html#Co...;.
We present here a selection of configuration options:
+ The default configuration file for <systemitem
class="daemon">chronyd</systemitem> is
<filename>/etc/chrony.conf</filename>. The <option>-f</option>
option can be used to specify an alternate configuration file path. See the <systemitem
class="daemon">chronyd</systemitem> man page for further options. For a
complete list of the directives that can be used see <ulink
url="http://chrony.tuxfamily.org/manual.html#Configuration-file"...
pubwork="webpage">http://chrony.tuxfamily.org/manual.html#Co...;.
Below is a selection of configuration options:
<variablelist>
<varlistentry>
<term>Comments</term>
@@ -175,7 +175,7 @@ Optionally specify a host, subnet, or network from which to allow
<systemitem cl
<term>cmdallow</term>
<listitem>
<para>
- This is similar to the <command>allow</command> directive (see
section <command>allow</command>), except that it allows control access
(rather than <systemitem class="protocol">NTP</systemitem> client
access) to a particular subnet or host. (By <quote>control access</quote> is
meant that <application>chronyc</application> can be run on those hosts and
successfully connect to <systemitem
class="daemon">chronyd</systemitem> on this computer.) The syntax is
identical. There is also a <command>cmddeny</command> all directive with
similar behavior to the <command>cmdallow</command> all
directive.</para>
+ This is similar to the <command>allow</command> directive (see
section <command>allow</command>), except that it allows control access
(rather than <systemitem class="protocol">NTP</systemitem> client
access) to a particular subnet or host. (By <quote>control access</quote> is
meant that <application>chronyc</application> can be run on those hosts and
successfully connect to <systemitem
class="daemon">chronyd</systemitem> on this computer.) The syntax is
identical. There is also a <command>cmddeny all</command> directive with
similar behavior to the <command>cmdallow all</command>
directive.</para>
</listitem>
</varlistentry>
@@ -203,7 +203,7 @@ Optionally specify a host, subnet, or network from which to allow
<systemitem cl
<para>
An example of the command is:
<screen>local stratum 10</screen>
-A large value of 10 indicates that the clock is so many hops away from a reference clock
that its time is fairly unreliable. Put another way, if the computer ever has access to
another computer which is ultimately synchronized to a reference clock, it will almost
certainly be at a stratum less than 10. Therefore, the choice of a high value like 10 for
the <command>local</command> command prevents the machine’s own time from ever
being confused with real time, were it ever to leak out to clients that have visibility of
real servers.</para>
+A large value of 10 indicates that the clock is so many hops away from a reference clock
that its time is unreliable. If the computer ever has access to another computer which is
ultimately synchronized to a reference clock, it will almost certainly be at a stratum
less than 10. Therefore, the choice of a high value like 10 for the
<command>local</command> command prevents the machine’s own time from ever
being confused with real time, were it ever to leak out to clients that have visibility of
real servers.</para>
</listitem>
</varlistentry>
<varlistentry>
@@ -261,7 +261,7 @@ A large value of 10 indicates that the clock is so many hops away from
a referen
</listitem>
</varlistentry>
</variablelist>
-
+
@@ -318,9 +318,9 @@ After the first clock update, <systemitem
class="daemon">chronyd</systemitem> wi
<para>
One of <systemitem class="daemon">chronyd</systemitem>'s tasks
is to work out how fast or slow the computer’s clock runs relative to its reference
sources. In addition, it computes an estimate of the error bounds around the estimated
value.
-If the range of error is too large, it probably indicates that the measurements have not
settled down yet, and that the estimated gain or loss rate is not very reliable.
+If the range of error is too large, it indicates that the measurements have not settled
down yet, and that the estimated gain or loss rate is not very reliable.
-The <command>maxupdateskew</command> parameter allows the threshold for
determining whether an estimate may be so unreliable that it should not be used. By
default, the threshold is 1000 ppm.
+The <command>maxupdateskew</command> parameter is the threshold for
determining whether an estimate is too unreliable to be used. By default, the threshold is
1000 ppm.
The format of the syntax is:
@@ -360,7 +360,7 @@ The format of the syntax is:
<para>
The format of the syntax is:
<screen>stratumweight
<replaceable>dist-in-seconds</replaceable></screen>
-By default, <replaceable>dist-in-seconds</replaceable> is 1 second. This
usually means that sources with lower stratum will be preferred to sources with higher
stratum even when their distance is significantly worse. Setting
<command>stratumweight</command> to 0 makes <systemitem
class="daemon">chronyd</systemitem> ignore stratum when selecting the
source.
+By default, <replaceable>dist-in-seconds</replaceable> is 1 second. This
means that sources with lower stratum are usually preferred to sources with higher stratum
even when their distance is significantly worse. Setting
<command>stratumweight</command> to 0 makes <systemitem
class="daemon">chronyd</systemitem> ignore stratum when selecting the
source.
</para>
</listitem>
</varlistentry>
@@ -375,7 +375,7 @@ The format of the syntax is:
<screen>rtcfile /var/lib/chrony/rtc</screen>
-<systemitem class="daemon">chronyd</systemitem> saves information
in this file when it exits and when the <command>writertc</command> command is
issued in <application>chronyc</application>. The information saved is the
RTC’s error at some epoch, that epoch (in seconds since January 1 1970), and the rate at
which the RTC gains or loses time. Not all real-time clocks are supported as their code is
system-specific. Note that if this directive is used then real-time clock should not be
manually adjusted as this would interfere with
<application>chrony</application>'s need to measure the rate at which the
real-time clock drifts if it was adjusted at random intervals.
+<systemitem class="daemon">chronyd</systemitem> saves information
in this file when it exits and when the <command>writertc</command> command is
issued in <application>chronyc</application>. The information saved is the
RTC’s error at some epoch, that epoch (in seconds since January 1 1970), and the rate at
which the RTC gains or loses time. Not all real-time clocks are supported as their code is
system-specific. Note that if this directive is used then the real-time clock should not
be manually adjusted as this would interfere with
<application>chrony</application>'s need to measure the rate at which the
real-time clock drifts if it was adjusted at random intervals.
</para>
</listitem>
</varlistentry>
@@ -689,7 +689,7 @@ This indicates the mode of the source.
<literal>^</literal> means a server, <lit
<term>S</term>
<listitem>
<para>
-This column indicates the state of the sources. <quote>*</quote> indicates
the source to which <systemitem class="daemon">chronyd</systemitem>
is currently synchronized. <quote>+</quote> indicates acceptable sources which
are combined with the selected source. <quote>-</quote> indicates acceptable
sources which are excluded by the combining algorithm. <quote>?</quote>
indicates sources to which connectivity has been lost or whose packets do not pass all
tests. <quote>x</quote> indicates a clock which <systemitem
class="daemon">chronyd</systemitem> thinks is is a falseticker (that is
to say, its time is inconsistent with a majority of other sources).
<quote>~</quote> indicates a source whose time appears to have too much
+This column indicates the state of the sources. <quote>*</quote> indicates
the source to which <systemitem class="daemon">chronyd</systemitem>
is currently synchronized. <quote>+</quote> indicates acceptable sources which
are combined with the selected source. <quote>-</quote> indicates acceptable
sources which are excluded by the combining algorithm. <quote>?</quote>
indicates sources to which connectivity has been lost or whose packets do not pass all
tests. <quote>x</quote> indicates a clock which <systemitem
class="daemon">chronyd</systemitem> thinks is a
<firstterm>falseticker</firstterm> ( its time is inconsistent with a majority
of other sources). <quote>~</quote> indicates a source whose time appears to
have too much
variability. The <quote>?</quote> condition is also shown at start-up,
until at least 3 samples have been gathered from it.</para>
</listitem>
</varlistentry>
@@ -723,7 +723,7 @@ This shows the stratum of the source, as reported in its most recently
received
<term>Reach</term>
<listitem>
<para>
- This shows the source’s reachability register printed as octal number. The register
has 8 bits and is updated on every received or missed packet from the source. A value of
377 indicates that a valid reply was received for all from the last eight transmissions.
+ This shows the source’s reach register printed as an octal number. The register has 8
bits and is updated on every received or missed packet from the source. A value of 377
indicates that a valid reply was received for all of the last eight transmissions.
</para>
</listitem>
</varlistentry>
@@ -755,7 +755,7 @@ This shows the stratum of the source, as reported in its most recently
received
The optional argument <option>-v</option> can be specified, meaning verbose.
In this case, extra caption lines are shown as a reminder of the meanings of the columns.
<screen>~]$ <command>chronyc sourcestats</command>
-
+
210 Number of sources = 1
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
@@ -858,7 +858,7 @@ Where <replaceable>commandkey-password</replaceable> is
the command key or passw
<section id="sect-Setting_up_chrony_for_different_environments">
<title>Setting Up chrony for Different Environments</title>
-
+
<section
id="sect-Setting_up_chrony_for_a_system_which_is_infrequently_connected">
<title>Setting Up chrony for a System Which is Infrequently
Connected</title>
@@ -872,20 +872,12 @@ The command key ID is generated at install time and should
correspond with the <
</para>
<para>
- <orderedlist>
- <listitem>
- <para>
Using your editor running as <systemitem
class="username">root</systemitem>, add the addresses of four
<systemitem class="protocol">NTP</systemitem> servers as follows:
- <screen>
-server
0.pool.ntp.org offline
+ <screen>server
0.pool.ntp.org offline
server
1.pool.ntp.org offline
server
2.pool.ntp.org offline
-server
3.pool.ntp.org offline
-</screen>
+server
3.pool.ntp.org offline</screen>
The <option>offline</option> option can be useful in preventing systems from
trying to activate connections. The <application>chrony</application> daemon
will wait for <application>chronyc</application> to inform it that the system
is connected to the network or Internet.
- </para>
- </listitem>
- </orderedlist>
</para>
</section>
@@ -974,15 +966,15 @@ From the remote systems, the system administrator can issue commands
after first
</para>
<para>
- The password or hash associated with the command key for a remote system is best
obtained by <systemitem class="protocol">SSH</systemitem>. That is
to say, an <systemitem class="protocol">SSH</systemitem> connection
should be established to the remote machine and the ID of the command key from
<filename>/etc/chrony.conf</filename> and the command key in
<filename>/etc/chrony.keys</filename> memorized or stored securely for the
duration of the session.
+ The password or hash associated with the command key for a remote system is best
obtained by <systemitem class="protocol">SSH</systemitem>. An
<systemitem class="protocol">SSH</systemitem> connection should be
established to the remote machine and the ID of the command key from
<filename>/etc/chrony.conf</filename> and the command key in
<filename>/etc/chrony.keys</filename> memorized or stored securely for the
duration of the session.
</para>
- </section>
+ </section>
</section>
-
+
<!--Topics, Reference-->
<section id="sect-additional_resources">
-
+
<title>Additional Resources</title>
<para>
The following sources of information provide additional resources regarding
<application>chrony</application>.
@@ -1024,14 +1016,14 @@ From the remote systems, the system administrator can issue
commands after first
</itemizedlist>
</section>
-<section id="s2-chrony_Useful_Websites">
- <title>Useful Websites</title>
+<section id="s2-chrony_Online_Documentation">
+ <title>Online Documentation</title>
<variablelist>
<varlistentry>
<term><ulink
url="http://chrony.tuxfamily.org/manual.html"/></term>
<listitem>
<para>
- The on-line user guide for <application>chrony</application>.
+ The online user guide for <application>chrony</application>.
</para>
</listitem>
</varlistentry>
@@ -1041,8 +1033,3 @@ From the remote systems, the system administrator can issue commands
after first
</section>
</chapter>
-
-
-
-
-